Dermestid beetle (carpet beetle; family Dermestidae)

Adults (family Dermestidae) are small, convex, oval to subglobose beetles. The dorsum is densely clothed with scale-like setae, yielding mottled patterns (often brown, black, white, or yellow). Head partly concealed by the pronotum; antennae short with a distinct 3-segmented club (capitate). Elytra rounded; legs short; body compact and robust. Larvae have a characteristic look: elongate, tapering posteriorly, and distinctly covered with a combination of short setae and longer hairs, often with subtle posterior tufting. Typically brownish, with three pairs of thoracic legs and transverse bands of setae on the terga.

A polyphagous secondary pest in granaries, it abrades the pericarp and germ of cracked or stressed kernels, generating fine frass and mealy dust. Feeding is superficial to shallow, leaving irregular nibbling and small, non-diagnostic perforations; sound kernels are seldom penetrated. Damage manifests as cumulative weight loss, reduced germinability, and quality downgrades driven by contamination rather than a signature lesion. Typical residues include larval exuviae, setae, and fecal pellets, which can impart off-odors, discolor seed surfaces, and provoke allergenic or irritant responses. Populations build on broken grain, oil-rich fractions, processing fines, and insect carrion, then disperse through storage. In short: diffuse surface feeding, fine dusting, and heavy filth contamination—noticeable and costly, yet not distinctive enough to diagnose on lesions alone.

Signs of infestation by Dermestidae (dermestid beetles; carpet beetles) in stored grain: - Larval exuviae (cast skins): the most frequent indicator; brittle, tan exuviae from successive larval instars, often with conspicuous bristles (setae). - Kernel injury: superficial grazing, pinholes/perforations, and partially hollowed kernels or germ. - Live stages: setose, brown larvae with posterior hair tufts and small, oval adults; frequently encountered at the grain surface, in seams, or in probe samples. - Odor: an unpleasant, musty to rancid smell associated with insect activity. Scientific name (family): Dermestidae.

Dermestid beetles are holometabolous (egg–larva–pupa–adult). After mating, females oviposit in cracks and crevices within infested substrates. Eggs hatch to mobile, setose larvae—the principal storage‑damaging stage—most often observed in facilities. Larvae pass through multiple instars and shed abundant exuviae in the commodity, which are frequently mistaken for live larvae. Pupation ensues in concealed sites, followed by adult emergence and dispersal. Most Dermestidae are primarily detritivores and reproduce optimally under moderate to high RH, whereas grain‑infesting Trogoderma are an exception, thriving in warm, dry grain.

Preferred habitat: synanthropic stored‑product sites—museums, silos, warehouses, mills, and food‑processing plants. Trogoderma are key storage pests; Dermestes and Attagenus also infest homes and other structures.

Many species of Dermestidae look alike and can be mistaken for one another.